1. Field of the Invention
The present invention relates to a thin film transistor liquid crystal display and, more particularly, to a thin film transistor liquid crystal display having a high aperture ratio.
2. Description of the Related Art
Currently, a liquid crystal display (LCD) with the advantages of low power consumption, thin thickness, light weight, and low driving voltage, has been put to many uses, such as personal computers, navigation systems, projectors, viewfinders and portable devices (watches, electronic calculators, and televisions).
Depending on the dielectric anisotropy and conductive anisotropy of the liquid crystal (LC) molecules, when an electric field is applied on the LCD, the alignment of the LC molecules is changed to display images. In active matrix LCD technology, a thin film transistor (TFT) is employed as a switch device in a TFT-LCD, and has the advantages of low power consumption, light weight, and low driving voltage.
FIG. 1 is a plane view showing a layout of a conventional TFT-LCD. In the TFT-LCD, a TFT structure comprises a gate electrode protruding from a gate line 120 and a source/drain electrode 180. Also, an ITO layer 200 is patterned on a pixel area and covers a part of the gate line 120. Particularly, since the gate electrode and the source/drain electrode 180 extend toward the pixel area, the TFT structure is viewed as a stretching-tongue type. As the TFT-LCD is continuously developed toward a high resolution, a high luminescence, a thinner form, a lighter weight and a smaller size, however, the aperture ratio of the TFT-LCD becomes smaller and smaller, resulting in a decreased transmittance. The pixel capacitance also becomes smaller to increase the coupling capacitance (Cgs is used as a symbol for the coupling capacitance in FIG. 1) generated between the gate electrode and the drain electrode, resulting in a deteriorated image performance. Thus, a method of increasing the aperture ratio and decreasing the coupling capacitance solving the aforementioned problems is called for.